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Back to the Future...

pvmb
Rising Star
Posts: 377
Thanks: 32
Fixes: 1
Registered: ‎12-02-2014

Back to the Future...

Whoa! Something has happened to my broadband.

After previous long term problems were solved a year or more ago everything has been going splendidly. I was back to my expected ~18Mbps download and the last I remember the router had been up continously for 77 days - and this after a day of repeated power cuts and an unnecessary reboot by me some time last year. Today I noticed "Router Up 2 days" and the speed was back down to ~15MBps. What gives? A broadband drop out or power failure during the night? A couple of reboots later and it hasn't shifted from its new, lower level. After reboot the Downstream SNR starts out at 3dB and then gracefully curves up to the 6dB level.

Checking the Bitloading graph in DSLstats, it looks a bit of a mess. As well as the normal missing low level tone (pilot tone) and the few, obvious inverted spectral line type 'holes' caused by AM transmissions I now have several individual tones knocked out in places that were OK previously, also the higher level ADSL tones are clearly at a lower level and the cut off is somewhat lower in frequency.

The usual tests do not seem to indicate any obvious problems my end. What could be going on? A few days ago, I cannot remember how many now, I had two Openreach vans on site (something to do with 'Superfast Optical Broadband'?) dealing with a neighbour. I noticed they had taken up a BT duct cover and were peering inside. I have to say, although it was nothing to do with me, it made me apprehensive at the time. Was I wrong?

Something has happened, presently it doesn't seem to be anything to do with me. I want my 18Mbps back!

Any opinions?

TIA

14 REPLIES 14
Gel
All Star
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Registered: ‎02-08-2007

Re: Back to the Future...

pvmb
Rising Star
Posts: 377
Thanks: 32
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Registered: ‎12-02-2014

Re: Back to the Future...

Yes, thanks Gel, that was what I was aiming to do. Though probably didn't get up quite early enough. Wink

Here is how things are at the moment:

 

After turning the router off overnight I rebooted this morning and am still getting the lower speed (15881 kbps) corresponding to a 6 dB noise margin, rather than my more usual ~3 dB.

Yesterday I later noticed something very wrong with the Forward Error Correction plot in DSLstats. Rather than the normal spiky plot, no more than ~3000 FEC per min, shortly after boot up it had shot up to something under (log plot) 1 million FEC per min. Furthermore it was an unchanging constant level, a straight line at this level continuously. It looked more like a SNR plot than a FEC plot.

This morning FEC had returned to normal, with spikes up and down below the 3000 FEC per min level. The Bitloading is still not 'clean', with the new extra missing tones.

Something seems to have changed. What I am wondering is, could this be due to cross-talk, say from a newly installed FTTC on a neigbouring circuit?

Of course I do realise I cannot actually report a fault, as the line would be considered within specifications.

Baldrick1
Seasoned Hero
Posts: 5,990
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Registered: ‎30-06-2016

Re: Back to the Future...

Have you tried a quiet phone line test? Ring 17070 with a corded phone and select option 2.

ejs
Community Veteran
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Registered: ‎10-06-2010

Re: Back to the Future...

I think the only way to infer if extra noise might be crosstalk is to monitor the SNRM and see if it occasionally spikes upwards briefly, consistent with the temporary absence of the crosstalk while someone else's modem is retraining or rebooting. That's assuming they leave their modem on at all times. If it's someone who switches theirs off when they're not using it, then you'll be able to see when it's on or off from monitoring the SNRM.

pvmb
Rising Star
Posts: 377
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Registered: ‎12-02-2014

Re: Back to the Future...

Still seems much the same up to today.

Yes, thanks Baldrick1, I have checked the Quiet Line Test and there is no apparent problem. I have also carried out line
tests via my phone (...!) and it's reporting "Line testing OK"... I have run the router from the BT test socket
(inconveniently and for a short time) and there was no obvious difference.

Thanks, ejs, for advice about checking for cross-talk. Looks like one way or another I will have to keep DSLstats running.

I notice that Broadband is once again being dropped at odd times - last time around 4am this morning. This is very different
to the last year or so when it could stay on for an apparently unlimited time, but is a return to the previous situation I endured for so long. But at present I cannot identify anything actually faulty. Also, frustratingly, as was initially the case previously.

Broadband is great when it is running faultlessly, very frustrating when it starts to play up!

pvmb
Rising Star
Posts: 377
Thanks: 32
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Registered: ‎12-02-2014

Re: Back to the Future...

From the sublime to the ridiculous (or the other way around).

Currently, FEC errors - recently peaking at ~800,000 per min continuously - have now totally disappeared, flatlining at absolutely zero!

BD
Plusnet Help Team
Plusnet Help Team
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Registered: ‎24-04-2017

Re: Back to the Future...

Hi there, sorry to hear you're having broadband issues. Checking your connection from this side although everything is looking where it should be in terms of speed and profile settings there are signs of errors flaring up at times which looking at the amount of drops over the last few days I imagine flares up more during the evenings and when you've been spotting the performance issues also?

 

Profile Info: WBC 160K - 24M No delay (INP0 ) 6dB Downstream, UC No delay (INP 0) 6dB Upstream (ADSL2+)
Sync Status: Circuit In Sync
General Information
NTE Status:   NTE Power Status: PowerOn Bypass Status:  
 
  Upstream DSL Link Information Downstream DSL Link Information
Loop Loss: 14.5 28.5
SNR Margin: 6.5 6.1
Errored Seconds: 0 3
HEC Errors: 0  
Cell Count: 1166 3021
Speed: 1263 15552
 
Maximum Stable Rate (KBPS): 15904 Fault Threshold Rate (KBPS): 12723
Mean Time Between Retrains (Seconds): 61115 Mean Time Between Errors Upstream (Seconds): 886
Indicative Line Quality: A Mean Time Between Errors Downstream (Seconds): 66


If you haven't already, the one check I'd recommend we do before raising a fault and getting an engineer out to investigate further would be plug the connection into your test socket. This rules out internal wiring, face plates and extension sockets as being the cause. How to locate the test socket and set your connection into it can be found here:
https://community.plus.net/t5/Library/Testing-From-The-Master-Socket/ba-p/1322242

Let us know how it goes in that set-up and given the rarity of the drops over the last few days I'd advise leaving it in there for 1-3 days to see if the issue persists. If you notice the drops are ongoing in that time let us know as we wouldn't have to wait the full 3 days.

Kind regards,

Ben

 Ben Devine
 Plusnet Help Team
pvmb
Rising Star
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Registered: ‎12-02-2014

Re: Back to the Future...

Thanks Ben.

I did try the test socket for a short while and things looked much the same. I will try it for a few days. As this is not very convenient and prevents me easily using a printer I will leave it until the weekend, probably starting from Saturday.

The drop-outs seem to occur at varying times, about 11am today, a few days ago around 4am. Currently, on the 6dB profile, I am getting low levels of errors and zero FEC errors.

RandallFlagg
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 1,915
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Registered: ‎11-01-2018

Re: Back to the Future...

Hi @pvmb,

 

I'm just checking in to see how you're getting on with this.

 

I've checked your account and it appears that there have been no drops for the past three days. How are things on your side?

 

Let us know if you need any further support.

 

Kind regards,

Dave

pvmb
Rising Star
Posts: 377
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Registered: ‎12-02-2014

Re: Back to the Future...

Yes thanks. Four days now on the test socket without drop outs.

There are few errors, though the SNR is still 6dB giving a download speed of currently 15613 Kbps. Less apparent Bitswaps, though the Bitloading plot looks to me much the same as before. I'll try again on the usual extension socket over the next few days and see what that looks like.

I decided to explore the local RF environment in the Medium band and was rather horrified. To me it sounded dreadful. Using a mains FM/AM tuner there sounds to be loads of static and for instance, on a local station at 1152KHz, there is superimposed a large buzz. This is the same on a portable transistor radio (but also mains powered) and here turning the receiver shows a pronounced directional effect. My car radio when on AM also shows this buzz. I may get a battery for the portable to explore this further.

Trouble is, I never use AM so have no benchmark as to whether this is now normal or something new.

pvmb
Rising Star
Posts: 377
Thanks: 32
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Registered: ‎12-02-2014

Re: Back to the Future...

I switched back from the test socket to the usual extension several days ago. The extension is a bit more error prone than the test socket but otherwise things seemed to have calmed down now. I don't know what was causing the problem before but it seems to have abated and I do not seem to have had any unexpected line drops for three days.

Unfortunately, as I am still on a 6 dB noise margin, my speed is still around 15000 kbps not 18Mbps. I can't now remember how I got my 18Mbps back last time. Do I just wait and the NM will automatically drop to 3dB after about 10 days? Or do I need to reboot the router after a week or so?

adamwalker
Plusnet Help Team
Plusnet Help Team
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Registered: ‎27-04-2007

Re: Back to the Future...

Hi there, 

 

I'm glad to see that things have re-stabilised. 

 

I've submitted a DLM reset so you should see some improvement to speeds soon. 

 

 

If this post resolved your issue please click the 'This fixed my problem' button
 Adam Walker
 Plusnet Help Team
pvmb
Rising Star
Posts: 377
Thanks: 32
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Registered: ‎12-02-2014

Re: Back to the Future...

Good, thanks.

 

The bad news? Unfortunately I've had another drop out! Unless that was something to do with the reset?

SammyM
Plusnet Help Team
Plusnet Help Team
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Registered: ‎22-01-2018

Re: Back to the Future...

Hello @pvmb

The drop out you experienced were due to the setting changed that my colleague performed. Your connection has remained stable since that point. Please let us know if any further issue arises. Cheesy

If this post resolved your issue please click the 'This fixed my problem' button
 SammyM
 Plusnet Help Team